Bitumen is a complex mixture of hydrocarbons and hydrocarbon derivatives, including aliphatic, naphthenic and aromatic compounds. It is an important component in road construction and is also used in roofing, waterproofing, adhesion and sealing. It is found in nature, but is typically obtained as a product of the refining of crude oil. In the first step of the refining process, crude oil is subjected to distillation at atmospheric pressure. Fractions from the crude oil are separated according to their boiling points. The heaviest fraction is a complex mixture of high molecular weight hydrocarbons and is known as long residue. The long residue is subjected to distillation at reduced pressure in a vacuum distillation column, producing gas oil, distillate and short residue. The short residue can be used to manufacture a variety of grades of bitumen.
Bitumen has to meet a variety of quality specifications before it can be marketed. Crude oils may be assessed by the laboratory preparation of bitumen samples to ensure that the bitumen obtainable from the crude oil is marketable. Laboratory preparation of bitumen samples is a slow and laborious process, requiring large samples of the crude oil to be sent to the laboratory. The present inventors have sought to provide a simpler method whereby the suitability of crude oil for bitumen production can be assessed.